Dispersion of fullerenes in phospholipid bilayers and the subsequent phase changes in the host bilayers

• Published in: Physica. B, Condensed matter Vol. 357; no. 1; pp. 193 - 198
• Main Authors: Jeng, U-Ser, Hsu, Chia-Hung, Lin, Tsang-Lang, Wu, Ching-Mao, Chen, Hsin-Lung, Tai, Lin-Ai, Hwang, Kuo-Chu
• Format: Journal Article Conference Proceeding
• Language: English
• Published: Amsterdam Elsevier B.V 28-02-2005; Elsevier
• Subjects: Analytical, structural and metabolic biochemistry; Biological and medical sciences; Biomolecules: types; Fullerene; Fundamental and applied biological sciences. Psychology; General and theoretical biochemistry; GISAXS; Phospholipid bilayers; SANS; 61.10.Kw; Fullerene; 87.15.Ya; SANS; GISAXS; 87.16.Dg; Phospholipid bilayers; Phospholipid; Small angle X ray scattering; Diffuse scattering; X ray reflection; Phase transformation; Small angle neutron scattering; Fullerenes; Electron density; 87.16.Dg Fullerene
• ISSN: 0921-4526; 1873-2135
• DOI: 10.1016/j.physb.2004.11.055

We have studied the structure and phase transition characteristics of the fullerenes (C
60)-embedded lipid bilayers. With small-angle neutron scattering (SANS), we have observed a degradation of bilayer ordering and a suppression effect on the phase transitions of the host vesicle bilayers of dipalmitoylphosphatidylcholine (DPPC), due to the embedment of fullerenes. The fullerene-embedded lipid system with substrate-oriented bilayers is also investigated using X-ray reflectivity and grazing incident small-angle X-ray scattering (GISAXS). In the depth direction, the multilamellar peaks observed in the X-ray reflectivity profile for the oriented DPPC/C
60 bilayers reveal a larger head-to-head distance
D
HH of 50.6
Å and a bilayer spacing
D of 59.8
Å, compared to the
D
HH=47.7
Å and
D=59.5
Å for a pure DPPC membrane measured at the same conditions. Furthermore, the lipid head layers and water layers in the extracted electron density profile for the complex system are highly smeared, implying a fluctuating or corrugated structure in this zone. Correspondingly, GISAXS for the oriented DPPC/C
60 membrane reveals stronger diffuse scatterings along the membrane plane than that for the pure DPPC system, indicating a higher in-plane correlation associated with the embedded fullerenes.